Creaseproofing cellulose-based fabrics

ABSTRACT

A method for rendering cellulose-based fabrics wrinkle resistant by impregnating the fibers of the fabric with a polymer builder, polymerizing the polymer builder in the impregnated fabric while the fibers are in a wet and swollen state, drying the fabric, and then depositing a film of silicone polymer on the fabric. Fabrics obtained from the process are described.

United States Patent 1191 Richardson 451 N 6, 1973 [54] CREASEPROOFING CELLULOSE-BASED 3,677,810 7/1972 Campbell et a1 117/1394 X FABRICS 3,546,006 12/1970 Verburg et a1 I l7/l39.4 X 3,598,633 8/1971 Rudman 117/76 T Inventor! Byron L. Richardson, Aiken, 5.0 2,802,754 8/1957 Ashby et a1. 117 76 T 3,434,875 3/1969 Smith et a1... 117/1394 [73} Asslgnee un'ted f' and 3,674,548 7 1972 Gagarine. 117/1394 X Manuiacmms New York 3,619,278 11/1971 Ogawa 117/1394 x 3,523,033 8/1970 Verburg et a1 117/1394 x 221 Filed; Sept. 16, 1971 Primary Examiner-Ralph Husack 1 PP N04 181,257 Att0rneyJules E. Goldberg et a1.

52 11.5. CI. 117/76 T, 117/139.4, 117/143 A, ABSTRACT 1 17/145 A method for rendering cellulose-based fabrics wrinkle [51] Int. Cl. D06m lS /52, D06m 15/72 resistant by impregnating the fibers of the fabric with [58] Field of Search l 17/139.4, 76 T, a polymer builder, polymerizing the polymer builder in 1 17/145, 143 A the impregnated fabric while the fibers are in a wet and swollen state, drying the fabric, and then depositing a [56] 7 References Cited film of silicone polymer on the fabric. Fabrics obtained UNITED STATES PATENTS 6/1958 Marsh et a1 117/1394 from the process are described.

8 Claims, N0 Drawings CREASEPROOFING CELLULOSE-BASED FABRICS BACKGROUND OF THE INVENTION process, a solution of the resin is impregnated into the fabric by padding. The fabric is then dried and baked at an elevated temperature during which curing of the resin takes place. This method is disadvantageous in that the treated cellulose fabrics usually exhibit a substantial deterioration in strength.

A more recent method of imparting crease resistance to cellulose-based fabrics, has been reported by N.R.S. Hollies, and NF. Getchell, Textile Research Journal 37, pages 70-76, 1964. This method, which they have called the .wet-fixation process consists essentially of impregnating the fabric with an aqueous, acidic solution of a polymerizable monomer, such as, for example, a melamine resin, and polymerizing the methylol resin within the interstitial spaces of the wet, swollen, fiber. After washing and drying, the fabric is then subjected to cross-linking with a suitable cellulose cross-linking reagent and a catalyst therefor. Alternately, the crosslinking agent can be introduced in the original impregnation step and then subsequently activated after drying of the fabric by treatment with an appropriate catalyst.

Cellulose fabrics treated by the wet-fixation process exhibit a degree of wrinkle resistance similar to that obtained with the pad/dry/cure method. Additionally, such fabrics exhibit a relatively higher retention of physical strength than fabrics treated with the pad/drylcure method.

Even so, the wet-fixation method does resultin significant deterioration of the fabric strength as compared with the untreated fabric.

It is also known that the deposition of a film of silicone polymer on a cotton fabric imparts to the fabric a moderate degree of wrinkle resistance without essentially any deterioration in the fabric strength. However, the wrinkle resistance is not nearly as greatas that obtained with the pad/dry/cure method or wet-fixation method. (See Bullock, J.B. and Welch, C.M. Textile Research Journal 35, pages 459-471 1965; and U.S. Pat. No. 3,434,875.

SUMMARY OF THE INVENTION I have discovered a new method for the treatment of cellulose-based fabrics which results in fabrics possessing both a degree of wrinkle'resistance equivalent to that obtained by the pad/dry/cure or wet-fixation processes described hereinabove and a substantially greater physical strength than fabrics treated by either of those methods.

This method comprises impregnating the fibers of a cellulose-based fabricwith a polymer builder, polymerizing the polymer builder in the impregnated fabric while said fibers are in a wet and swollen state, drying the fabric, and depositing a film of silicone polymer on the fabric.

I have also discovered a new-class of wrinkle-resistant fabrics which comprise a fabric having a cellulose content of at least about 20 percent based on the total weight of the fabric, which fibers contain between about 2 to 20 percent by weight of a polymerized polymer within the interstitial spaces thereof. The hydroxyl groups of said cellulose fibers may be in either a crosslinked or non-cross-linked state.

Additionally, the present invention comprises garments, draperies, bedspreads, and bedsheets made from such wrinkle-resistant fabric.

DESCRIPTION OF THE PREFERRED EMBODIMENT In accordance with the present invention, a polymer builder is impregnated into the fibers of a cellulose based fabric.

Any type of cellulose based or cellulose containing fabric may be used in the process of the present invention,such as, for example, cotton, blends of cotton with synthetics, acetate and acetate blends, etc.

Understandably, a certain amount of cellulosic component is needed in the fiber inasmuch as the improved crease-resistant properties result primarily from the modification of the cellulosic portion of the fiber. However, the amount varies depending on the polymer builder used, the other components of the fiber, etc. Preferably, the fabric possesses a cellulosic content of at least about 20 percent based on the weight of the total fabric.

Polymer builders suitable for use in the present invention include urea-formaldehyde resins, melamineformaldehyde resins, phenol-formaldehyde resins, hydroxyethyl methacrylate and the like.

The polymer builder may be applied to the fabric in 7 any one of the number of conventional methods such as for example, padding, dipping, spraying, etc.

Typically, for example, when the polymer builder is a methylolated melamine resin, the fabric is immersed in an aqueous bath containing from about 5 to 25 percent, preferably about 10 to 15 percent, and most preferably about 12 percent based on the total weight of the mixture, of the methylolated melamine solids. The pH of the bath should be below about 5, preferably below about 4 and most preferably in the range from about 1.5 to 3. Generally, the pH of the bath is easily adjusted by the addition of a mineral acid thereto.

After immersion, the cellulosic fabric is padded to a wet pick-up corresponding to the final amount of melamine solids desired on the fabric. Generally, the solids content of the fabric is desirably in the range from about 2 to 20 percent, preferably from about 4 to 12 percent and most preferably in the range from about 8 to 10 percent, based on the weight of the fabric. Usually, the fabric after immersion is padded to approximately an percent wet pick-up based on the weight I of the fabric.

The polymerization of the melamine is dependent on both the pH of the bath and the temperature. The lower the pH, the more rapid the polymerization reaction. Alternatively, the higher the temperature, the more rapid qthe polymerization reaction. Generally, the polymerization step can be carried out at a temperature ranging from about room temperature to about 212F and for a time period from about 15 minutes to 24 hours. I have found it desirable to adjust the pH and the temperature so that the polymerization can be accomplished in a period from about 8 to 24 hours at room temperature.

The polymerization step is carried out in such a manner that the fabric remains in a wet, swollen state during the entire period. Thus, for example, in order to prevent evaporation of water from the fabric, the fabric may be wrapped in plastic or otherwise encapsulated so that no moisture is allowed to escape during the polymerization period. As a result, the fibers are maintained in a wet, swollen condition during the polymerization such that the resin polymerizes to a great extent within the interstitial spacing of the fibers.

After the polymerization period, the fabric is washed, desirably with an alkaline solution to neutralize any residual acid thereon. For example, in a mill operation such neutralization with washing would be achieved during the alkaline soaping in the back washing procedure.

After washing, the fabric is dried in the conventional manner, usually at a temperature in the range from about 100 to 350F.

As noted hereinabove, other types of polymer builders may be used and the amount of such polymer builder used expressed as its content by weight on the final fabric as well as the specific polymerization conditions depend on the specific polymer builder used. Generally, it is desirable that the fabric obtained after processing contain between about 2 to percent by weight of the polymer therein, based on the weight of the fabric.

After the fabric is dried, a film of a silicone polymer is applied to the fabric. The silicone polymer or elastomer may be applied by a number of methods well known to the art. Preferably, it is applied from an organic solvent solution. After application, the fabric with the silicone polymer thereon is dried and cured.

As used herein, the term silicone elastomer means any type silicone polymer composition which can be cast on a glass plate, dried, and if necessary, cured to give a continuous film having elastomeric properties and moderate strength such that the film does not powder or disintegrate when rubbed lightly by hand.

Typically useful silicone elastomers are described in US. Pat. No. 3,076,726, and are generally within the class known as methyl polysiloxanes. Additionally, suitable elastomers are described in US. Pat. No. 3,434,875, incorporated herein by reference.

Preferred silicone elastomers for use herein are characterized by a very high molecular weight although low molecular weight silicones may also be used so long as the composition is appropriately modified or the conditions selected so as to give a continuous film having the characteristics indicated when the silicone is cast on glass, dried, and if necessary, cured.

The elastomer may be applied to the fabric by conventional methods such as a kiss roll, spraying, knife coating, padding,'etc. Usually the amount of elastomer solids added to the fabric depends on a number of conditions such as the fabric construction, the type of elastomer used, etc. Generally, the solids add-on is in the range from about 0.1 to 30 percent and preferably from about 0.6 to 16 percent, based on the weight of the original fabric.

Solvent systems suitable for use in the application of the silicone elastomer include any type of inert solvent which will dissolve the elastomer, such as, for example,

hydrocarbon or chlorinated hydrocarbon solvents, e.g. mineral spirits, perchloroethylene, and the like. Particularly suitable is a solvent falling within the classification known as Stoddard solvent. Such a solvent is defined by Commerical Standard C.S. 3-41 and A.S.T.M. D 484-52.

After applying the elastomer in the solution or by whatever method is used, the fabric can be dried in a conventional manner such as air drying or heating. Temperature and time of drying may be selected as desired and can be widely varied so long as all the solvent is removed before curing.

Methods for curing the silicone elastomers and polymers suitable for use in the present invention are well known and depend on the particular elastomer as well as the equipment used. Thus for example, curing times in the range from about 30 minutes at 250F or 1-2 minutes at 425F may be used. Alternatively, if a different type of curing oven is used, such as, a roller type oven, heating at a temperature in the range from about 250 to 375F for about 1 to 10 minutes may be sufficient. Additionally, the silicone elastomers may, if desired, be used in combination with other high polymer elastomers, such as, for example, polyurethanes, polysulfides, or acrylics.

In addition, to the characteristics noted hereinabove for suitable silicone elastomers, it is desirable that the material not be tacky but possess some lubrication or tack-free properties and that it be resilient and possess good recovery from elongation or deformation. Preferably the recovery when tested as a film is in the range from about to percent.

If desired, after drying of the fabric subsequent to polymerization of the polymer builder, but prior to coating with the silicone polymer, the fabric may be subjected to a cross-linking step in accordance with the wet-fixation process. Such cross-linking treatment may be carried out in the manner described in the article by N.R.S. Hollies and N.F. Getchell noted hereinabove. The cross-linking treatment can be carried out either by dry or wet methods with various types of cross-linking agents such as dihydroxydimethylolethylene urea and methylolated carbamates. Additionally, of course, a suitable catalyst is included in the treatment.

Alternately, as noted hereinabove in the description of the wet-fixation process, it is possible to include the cross-linking agent in the original impregnation step with the polymer builder. In this case, the fabric may be treated with the catalyst activator subsequent to washing and drying but prior to coating with the silicone elastomer. However, the cross-linking agent may be included in the impregnation step without the catalyst treatment.

Thus, cross-linking of the hydroxyls of the cellulosic component is not critical to the achievement of superior wrinkle resistant properties in the fabric when treated in accordance with the process of the present invention.

Additionally, various types of adjuvants well known to the art may be added to the impregnation solution. Thus, for example, softeners may be added to improve the hand of the fabric. Softeners suitable for use in the present process are described in detail in Self- Smoothing Fabrics by J .T. Marsh, Chapman and Hall, Ltd., London, 1962, Chapter 10.

Additionally, the present invention comprises a wrinkle resistant fabric consisting of cellulose-containing fibers, having between about 2 to 20 percentby weight based on the total weight of the fabric of a polymer within the interstitial spaces of the fibers, said polymer preferably being urea-formaldehyde resin, melamineformaldehyde resin, phenol-formaldehyde resin, or 'hydroxyethyl methacrylate and wherein the fibers of the fabric are coated with a high molecular weightsilicone polymer as described hereinabove, and wherein the cellulosic hydroxyl groups of the fabric may be either in a cross-linked or non-cross-linked state.

Preferably, the fabric has a cellulose content of at least about 20 percent based on the total weight of the fabric.

The fabric of the present invention :may beused in any type of end use wherein wrinkle resistance is desired. Thus, for example the fabrics of the present invention may be in the form of garments, draperies, bedspreads, bedsheets, etc.

centistokes at 77F (Dow Corning FC-227) in xylene and 0.2 percent of an organo tin salt (Dow Corning Catalyst 27) xylene, all percentages being based on the total weight of the bath. After immersion, the sample was squeezed to a l00percent wet pick-up through pad rolls. The fabric was then dried for 10 minutes at l00l05C. and cured for 10 minutes at about 165C.

Sample 'C, which is a fabric prepared in accordance with the present invention, was prepared by first treating the fabricexactly in accordance with the procedure set forth under Sample A. After the final drying, Sample C was then coated with a silicone polymer in accordance with the procedure set forth for Sample B.

A fourth sample, designated Control was not subjected to any treatment and was held for comparison purposes.

The foregoing described Samples A, B, C, and Control were then subjected to the tests as set forth hereinabove. The results of the foregoing tests are set forth inTable I.

TABLE I The following examples serve to illustrate the present invention.

The fabrics produced in the examples were characterized using the following tests:

1. Monsanto Dry Crease Recovery AATCC test method 66-1968 2. Wyzenbeek Abrasion ASTM D1 l75-64T (oscillatory cylinder-400-J metalite cloth as abraidant) 3. Tensile Strength ASTM Dl682-64 (ravelled strip) 4. Tear Strength ASTM Dl424-63 5. Stoll Flex Abrasion ASTM Dl-l 75-64T (flexing and abrasion two pound tension, 1/2 pound head weight) 6. Water Repellency AATCC test method 22-1967 Example 1 Three samples of desized, bleached and mercerized 136x64 cotton broadcloth, designated hereinafter Samples A, B, and C, were treated as follows:

Sample A was immersed in an aqueous solution containing 20 percent of a methylated methylol melamineformaldehyde condensate (Resloom M-75 Monsanto Company), 0.1 percent of an ethylene oxide condensate of monylphenol (Valdet 56l-Valchem Company) and 1 percent concentrated HCl, all based on the weight of the bath. After immersion, the sample was squeezed through pad rolls to about an 80 percent wet pick-up. The fabric was then sealed in a plastic bag to prevent evaporation of moisture and was heated in an oven at 82C. for 15 minutes to polymerize the melamine condensate. The fabric was then washed in a sodium carbonate bath to neutralize any residual acid, washed with water, and dried. v

Sample B was immersed in a perchloroethylene bath comprising 9 percent of a high molecular weight silicone polymer having a viscosity of 10,000 to 25,000

dry crease Al'ler Wyzenbeek lill, lbs/in. l00 cycles Monsanto Stoll llux uhrusion l'ill. cycles l-llmendorl tear strength fill. grams 'l'ensilc abrasion. 0 cycles recovery Example 2 A sample of desized, bleached and mercerized 136X64 cotton broadcloth was impregnated with an aqueous solution containing 20 percent Resloom M75, 15 percent of a methylolated hydroxyethyl triazone (Valrez 99N-Valchem Corp.), 5 percent of a nonionic polyethylene emulsion containing 35 percent polyethylene (Valsof PE-45Valchem Corp.), 3 percent of a lanolin emulsion, containing 25 percent solids 0.1 percent of an ethylene oxide condensate of nonylphenol (Valdet 56l-Valchem Corp.) and l percent concentrated hydrochloric acid, all percentages being based on the weight of the total solution. Thereafter, the fabric was squeezed through pad rolls to an 80 percent wet pick-up. The fabric was then sealed in a plastic bag to minutes at about 10010SC and finally cured for 5 minutes at about 150C.

After the curing step, the fabric was coated with silicone using the identical procedure and materials as set methacrylate resins;

b. polymerizing the polymer builder in the impregnated fabric while said fibers are in a wet and swollen state;

forth under Sample B in Example 1 hereinabove. 5 c. drying the fabric; and then Properties of the fabric thus treated in contrast with d. depositing a film of silicone polymer on the fabric; those of the Control are set forth in Table 11. wherein said process is carried out in the absence of TABLE 11 Monsanto After dry crease Tensile Wyzenbeek Elmendorf Stoll flex recovery abrasion, fill, lbs./in. tear strength abrasion Sample ave. W F 0 cycles cycles fill, grams fill, cycles Treated sample... 304 .38.5 26.0 768 1.788 Control 182 44.0 8.1 1.288 1,190

AATCC 22 Spray Rating of 80 for treated sample. any cross-linking agent for cellulose.

2. The process of claim 1 wherein the silicone poly- Example 3 mer is a high molecular weight methyl polysiloxane A sample of desized, bleached and mercerized 78x78 elastomer polymer, said polymer being in a substancotton print cloth, was immersed in an aqueous solutially non-cross-linked state with respect to said fabric. tion of 20 percent Resloom-75, 15 percent Valrez 99 3. The process of claim 1 wherein the fabric is im- N, 5 percent Valsof PE 45, 0.1 percent Valdet 561 'and pregnated with sufficient polymer builder to produce a 1 percent hydrochloric acid based on the total weight 25 polymer content in the final fabric in the range from of the solution. The fabric after immersion was about 2 to 20 percent based on the total weight of the squeezed to 80 percent wet pick-up and then sealed in fabric. a plastic bag to prevent moisture evaporation. It was 4. The process of claim 1 wherein the polymer then heated in an oven at about 82 for 15 minutes to builder is melamine formaldehyde resin. polymerize the methylolated melamine. Thereafter, the 5. The process of claim 4 wherein impregnation step fabric was washed in a sodium carbonate bath to new (a) is carried out by immersing the fabric in an aqueous tralize any residual acid, washed with water, and dried. bath containing from about 5 to 25 percent based on In this case, the fabric was not treated with a crossthe total weight of the bath of methylolated melamine linking catalyst even though a cross-linking agent was solids, said bath having a pH below about 5, adjusting present in the immersion bath. the wet pick-up of the fabric to about 80 percent based The dried fabric was then coated with a silicone polyon the weight of the fabric and wherein subsequent to mer in accordance with the procedure set forth for the polymerization step (b), and prior to drying step Sample B in Example 1. (c), the fabric is washed with an alkaline solution to The property exhibited by the fabric in comparison neutralize residual acidity. with a Control" are set forth in Table Ill. 40 6. The process of claim 5 wherein the polymerization TABLE 111 Monsanto After dry crease Tensile Wyzenbeek Elmendorf Stoll flex recovery abrasion. fill. lbs/in. tear strength abrasion Sample ave. W+ F 0 cycles 100 cycles fill, grams fill, cycles Treated sample... 297 30.8 8.7 592 3,215 Control 200 34.7 13.8 1,040 1,678

Variations and modifications may, of course, be step is carried out at a temperature in the range from made, without departing from the spirit and scope of about room temperature to 212F and for a time period the present invention. from about 15 minutes to 24 hours.

1 claim: 7. The process of claim 4 wherein the fabric has a cell. A process for preparing a wrinkle resistant cellululose content of at last about 20 Percent by weight lose based fabric comprising: based on the totalweight of the fabric.

8. A wrinkle resistant fabric obtained b the rocess a. impregnating the fibers of a cellulose-based fabric f l l y p with an aqueous solution of a polymer builder seo c lected from the group consisting of ureaformaldehyde resins, melamine-formaldehyde resins, phenol-formaldehyde resins, and hydroxyethyl 

2. The process of claim 1 wherein the silicone polymer is a high molecular weight methyl polysiloxane elastomer polymer, said polymer being in a substantially non-cross-linked state with respect to said fabric.
 3. The process of claim 1 wherein the fabric is impregnated with sufficient polymer builder to produce a polymer content in the final fabric in the range from about 2 to 20 percent based on the total weight of the fabric.
 4. The process of claim 1 wherein the polymer builder is melamine formaldehyde resin.
 5. The process of claim 4 wherein impregnation step (a) is carried out by immersing the fabric in an aqueous bath containing from about 5 to 25 percent based on the total weight of the bath of mEthylolated melamine solids, said bath having a pH below about 5, adjusting the wet pick-up of the fabric to about 80 percent based on the weight of the fabric and wherein subsequent to the polymerization step (b), and prior to drying step (c), the fabric is washed with an alkaline solution to neutralize residual acidity.
 6. The process of claim 5 wherein the polymerization step is carried out at a temperature in the range from about room temperature to 212*F and for a time period from about 15 minutes to 24 hours.
 7. The process of claim 4 wherein the fabric has a cellulose content of at least about 20 percent by weight based on the total weight of the fabric.
 8. A wrinkle resistant fabric obtained by the process of claim 